Home networks are becoming more common and desirable for connecting computers within a home. One type of home network is the home phone line network which uses telephone lines typically installed in residence homes for communication between computers in the home. The Home Phone Line Networking Alliance (HPNA) has published a specification to standardize the behavior of home phone line networks.
FIG. 1 illustrates a home phone line network in accordance with the present invention. The preferred embodiment of the network complies with the Home Phoneline Networking Alliance specification version 2.0 (HPNA 2.0). The network allows multiple computers to communicate through telephone wires typically installed in residential homes. The network comprises a control chip 100. The chip 100 further comprises a Media Independent Interface (Mu) 106, a Media Access Control (MAC) 108, and a Physical Layer (PHY) 110. The chip 100 implements the HPNA 2.0 specification. The chip 100 receives a signal containing data packets through the telephone wires via a phone jack 102. There is an analog front end (AFE) 104 which processes the signal between the chip 100 and the telephone wires. The chip 100 then processes the packets received in the signal from the AFE 104, and outputs a signal to the Host MAC 112 or to an Ethernet controller 114.
As is known in the art, a priority tag, or “Q Tag”, may be inserted into the header of a frame to provide information which may be used to prioritize the frame in relation to other frames. However, under HPNA 2.0, the frame may contain an additional 8-byte Limited Automatic Repeat Request (LARQ) in its header before the priority tag. The LARQ conveys link layer priority information and provides a negative acknowledgment protocol to increase the speed of frame retransmission. The Ethernet protocol used by the Ethernet controller 112 does not recognize or expect the LARQ header. When a HPNA frame with the LARQ header and the Q Tag is sent to the Ethernet controller 114, the Ethernet controller 114 counts the bytes to the expected Q Tag location, but the Q Tag is actually 8 bytes further down the frame. The Ethernet controller 114 thus erroneously believes the frame has no priority information.
Accordingly, there exists a need for a mechanism to strip the LARQ header to support frame priority. The present invention addresses such a need.